The present invention relates to a blood storage container, and more particularly to a blood storage container for use in an open-type pump oxygenator circuit or the like.
When a surgical operation is effected on the chest of a patient, an oxygenator is often used recently in connection with an extracorporeal blood circulation circuit in bypassing relation to the lung of the patient, and carbon dioxide is removed from the blood of the patient and fresh oxygen is added to the blood by the oxygenator.
The extracorporeal blood circulation circuit includes a blood storage container for temporarily storing the blood so that air bubbles produced during the circulation of the blood will be removed from the blood, or the rate of circulation of the blood will be prevented from dropping due to the bending of a tube of the extracorporeal blood circulation circuit. Blood storage containers now in use in the arm are roughly classified into a closed-type soft bag container which is made of a soft material and stores the blood in a hermetically sealed condition, and an open-type hard shell container which is made of a hard material and stores the blood in an open or vented condition. The soft bag container is advantageous in that it has no blood-air interface, but disadvantageous in that it cannot hold a large amount of blood and cannot give an exact indication of how much blood is stored therein.
The hard shell container can store a large amount of blood and allows the user to know the exact amount of blood stored therein. Other advantages of the hard shell container are that it can easily be united with an oxygenator thus permitting an extracorporeal blood circulation circuit to be arranged with ease, and also the blood can easily be debubblized when the extracorporeal blood circulation circuit is set up and primed. Japanese Laid-Open patent Publication No. 59-57661, for example, proposes a hard shell blood storage container which utilizes these advantages.
The conventional blood storage container which is united with an oxygenator, however, has no mechanism for removing air bubbles from the blood that ingresses into the container. Air bubbles must be removed from the blood in order to prevent the patient from suffering embolism. Therefore, the extracorporeal blood circulation circuit should be provided with a debubblizing mechanism in another region than the blood storage container.
It is nevertheless preferable to provide the blood storage container with a debubblizer for removing air bubbles from the stored blood, so that the extracorporeal blood circulation circuit will be made compact as a whole. Japanese Laid-Open patent Publication No. 62-258671 discloses a blood storage container which incorporates a blood debubblizer therein. The disclosed blood debubblizer comprises a foamed body integral with the blood storage container. The foamed body is of a hydrophobic nature to allow air bubbles in the blood to grow and be removed with a view to protecting the patient from embolism.
The foamed body positioned in the blood storage container is effective in removing relatively large air bubbles from the blood which has entered from a blood inlet into the foamed body. However, some very small air bubbles in the blood may pass through the foamed body and remain in the blood which returns into the body of the patient. When this happens, the patient may be afflicted with embolism owing to those very small air bubbles that remain trapped in the blood.